This invention relates to centrifugal fan systems, particularly such systems intended for use in buildings and other large structures.
Centrifugal fan systems are well known for a variety of applications and have been used in the past, for example, to provide fresh and/or heated air to a building by means of a plenum system. A centrifugal fan generally has a number of blades evenly distributed about a central rotation axis, these blades being mounted on two or more metal plates. The fan has a central inlet opening while the outlet of the fan is circumferential. The fan can be rotated by means of a central drive shaft which in turn is rotated by a suitable electrical motor.
U.S. Pat. No. 3,748,997 issued Jul. 31, 1973 to Tempmaster Corporation describes a penthouse type air conditioning unit that includes an acoustically insulated centrifugal fan that is separated from the fan motor. The fan impeller rotates about a horizontal axis in a plenum type chamber. The fan is supported by means of a framework which includes vertical uprights and compression vibration isolators support the entire fan assembly. The pressurized air from the fan flows downwardly through an outlet in the bottom of the fan compartment.
It is also known to employ an axial-type fan in an air distribution system for a building. An air distribution system using such a fan is taught in U.S. Pat. No. 4,295,416 issued Oct. 20, 1981 to Mitco Corporation. This patent teaches the use of an input flow concentrator and integral silencer disposed below the fan in a mixing plenum. The combined concentrator and silencer establishes a substantially axial symmetrical flow path for air from the plenum to an output port. The fan is coupled to this output port to drive the air to the main duct for distribution. A bank of heat exchange coils can be disposed adjacent to the input port of the concentrator/silencer.
It is an object of the present invention to provide a relatively inexpensive yet efficient centrifugal fan system to supply air to a building or other large structure.
It is a further object of the present invention to provide such a centrifugal fan system wherein the fan and the fan housing can readily be moved in order to provide access thereto for maintenance or repairs.
It is another object of the present invention to provide a relatively inexpensive centrifugal fan system for supplying air to a building, which system is reasonably efficient due to the use of an internal scroll-shaped wall extending around the fan and forming a plenum fan chamber, while at the same time the fan is reasonably quiet in its operation due to the use of sound insulating material around the scroll-shaped wall.